Lathe transmission and control mechanism



April 29, 1947.

w. F. GROENE 2,419,639

LATHE TRANSMISSION AND CONTROL MECHANIl ISM 14 Sheets-Sheet 1 Filed 001;. 6, 1943 INVENTOR. VHLUAM F- GROENE "whim ATTORNEY.

14 She ets-Sheet 2 W. F. GROENE LATHE TRANSMISSION AND CONTROL MECHANISM Filed Oct. 6, 1945 WW! I! April 29, 1947.

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mmvroze. wLuAM F. GRDENE ATTORNEY.

April 29,, 1947.v w, GROENE 2,419,539

LATHE TRANSEISSION M31) CONTROL MECHANISM Filea Oct. 6, 1943 14 Sheets-Shea; a

INVENTOR. w\ u.\m F.G;ROENE QMM8.

AT-rdRNe April 29, 1947. w. F. GROENE 2,419,639

LATHE TRANSMISSION AND CONTROL MECHANISM Filed Oct. 6, 1943 14 Sheets-Sheet 4 FFllXZ.

INVENTOR. WILLIAM EGROENE LOMML iM ATTORNEY.

W. F. GROENE LATHE TRANSMISSIION AND CONTROL MECHANISM April 29, 1947.

Filed Oct. 6, 1943 14 Sheets-Sheet s ATTORNEY.

April 29, 1947. T w. F. GROENE 2,419,639

LATHE TRANSMISSION AND CONTROL MECHANISM Filed Oct. 6, 1943 14 Sheets-Sheet 6 F IE1]:

as a f 1 13 '7 Q4 5 fi I6 q n an 11H 21s 6! I a2 2.2.8, 1 if H 22 --aas aaa INVENTOR.

WILLIAM F GROENE ATTO RNEY.

April 1947- w. F. GROENE LATHE TRANSMISSION mm CONTROL MECHANISM 14 Sheets-Sheet 7 Filed Oct. 6. i942,

INVENTOR. W\LL\M'\ F. GROENE ATTORNEY.

Aprfl 29, 1947. w. F. GROENE LATHE TRANSMISSION AND CONTROL MECHANISM 14 Sheets-Sheet 8 Filed Oct. 6. 194:5

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ATTORNEY.

April -29, 1947. GRQENE 2,419,639

LATHE TRANSMISSIOIN AND CONTROL MECHANISM Filed Oct. e, 1943 14 Sheets-Sheet 9 IN V EN TOR. WILUAM F. exam "pm :5. 91M

ATTORNEY.

April 29, 1947. w, GROENE 7 2,419,639

LATHE TRANSMISSION AND CONTROL MECHANISM FIiled Oct. 6, 1943 14 Sheets-Sheet 1O w Wm 4a 56 5 c,o 6%

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INVEN TOR. NILUAM F; GROENE ATTORNEY.

April 29, 1947. GROENE 2,419,639

LATHE TRANSMISSION AND CONTROL MECHANISM Filed Oct. 6, 1943 14 ,Sheets-Sheet 11 IN VEN TOR.

WILLIAM F.GROENE "mm & m-

ATTORNEY.

April 29,1947. w. F. GROENE 2,419,639

INVENTOR. wu.\.\m F. qaoem:

ATTORNEY.

' April 29, 1947. GROENE 2,419,639

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INVENTOR. WILUAM F. GROE-NE ATTORNEY.

Patented Apr. 29, 1947 LATHE TRANSMISSION AND coN'rnoL MECHANISM v William F. Groene, Cincinnati, Ohio, assignor to The R. K. Le Blond Machine Tool Company, Cincinnati, Ohio, a corporation of Delaware Application October 6 1943, Serial No. 505,143 37 Claims. (01. 82-29) This invention pertains to lathe transmission and control mechanism and is particularly related -to such mechanisms for tool room lathes. Such types of lathes are particularly adapted for machining parts having an infinite variety of characteristics. These lathes are required for machining of work of greatly varying diameters and shapes and must be capable of performing certain specific machining operations such as, chasing of coarse lead screws,.relieving attachment work on hobs and taps or the like, and the performance of an infinite variety of complex boring, turning and facing operations on every size and class of work within the range of the machine. Such a lathe obviously must be of extremely universal chara'cter both as to its adaptability to hold and cut difierent types of work and of rotating the work at a relatively great number of difierent speeds of widely varying range.

It is; therefore, the primary object of this invention to provide an improved lathe transmission especially adapted to meet these conditions in the tool room type of lathe. It is the principal idea to effect the spindle speed changes by a combination of electronic control apparatus for varying the'rnain drive motor for the lathe transmission through a very wide range of speed and to provide, in connection with this electronic controlled motor speed variation, a specially designed transmission for providing the necessary characteristics of spindle rotation in such a tool room type lathe.

The electronic control arrangement as contemplated in conjunction with this lathe transmission and controlmechanism is preferably of a type which may be supplied from a usual three phase alternating current supply, and by means of an appropriate transformer mechanism and electronic tube control apparatus a direct current motor may be actuated in a variety of accurately controlled variable speeds through a wide range. This electronically controlled variable speed D, C. motor is connected to the workspindle through a unique transmission mechanism which efiects, in this particular instance, two main speed variations for the work spindle in conjunction with the variable speed D. C. motor. However, it is not only necessary to provide a speed variation in the transmission mechanism associated with the driving motor but, also, to provide certain characteristics in the drive which permits of smooth cutting and accurate work particularly when rel- 2 and other irregularities and inaccuracies which come about in a mechanical gear drive transmission. when utilized at the high speed range. At low speed range for high power roughing cuts and on extremely large diameter work requiring slow speed, spindle rotation is efiected through a single back gear drive taking in account the complete.

variable speed range of the main drive motor.

In conjunction with the above variable speed electronically controlled motor and change speed power transmission for the work spindle, an especially arranged fine feed drive is provided when the work spindle is operating in the high belt speeds, the purpose of this fine feed being to provide a very accurate smooth feeding motion when utilizing modern day carbide cutting tools. This speed essentially is provided by belt driving atively high speeds are utilized with carbide cutting tools of modern day type.

The transmission mechanism associated with the variable speed electronically controlled motor is arranged to rotate the work spindle in direct belt drive through the entire range of high speeds to completely avoid the gear tooth marks, noise,

means from the main drive motor so as to provide relatively smooth input driving power initially to the feed mechanism during this'fine feed cutting at high spindle speeds.

Still another object is to provide, in conjunction with this unique lathe headstock transmission having the belt drive for rotating the work spindle at high speed and the back gear drive for rotating the work spindle at lower speeds, a belt drive arrangement from the main drive variable speed motor wholly outside of the headstock compartment containing the gear driving mechanism' on the lathe headstock transmission. In this way easy access to the belt driving mechanism is obtained while at the same time completely isolating thebelt drive from any lubricating dimculties which might otherwise occur should the belt 7 drive transmission be incorporated in the same compartment with the gear drive transmission.

Thus in this transmission mechanism it is an object to provide in a lathe, a variable speed D. 0. motor controlled by electronic control mechanism capable of operating from an alternating current source of supply and which variable speed motor is interconnected with a novel headstock transmission capable of providing direct drive high speed driving of the work spindle in conjunction with fine feeds, a back gear range of speeds variable through a series of speed changes by means 'of the variable speed main drive motor for the lower range of turning speeds, and to also provide in this transmission mechanism, means for rotating the work spindle within the lower portion of the low range of back gear speeds while providing at the same time a series of coarse thread feeding movements for the cutting tools. This latter arrangement is to permit the cutting of coarse threads or screws, or the like in the lathe while operating in a limited slow portion of the low range of speeds.

various diiferent functions which may be effected readily by the operator with a minimum of calculations or effect on his part. In this connection a novel dial arrangement is provided connected by suitable mechanical means with the headstock transmission for operating the various gear and clutch mechanisms in a predetermined sequential relationship to effect the high speed direct belt drive with fine feeds, the slower back gear drive with normal feeds, and the back gear drive through only a limited low portion of the range with coarse thread leads and feeds being provided. This control mechanism is so interrelated and interlocked that the correct sequential operation of the different functions may be readily obtained. Also, electrical interlock and control of the electronic operating mechanism of the main drive variable speed motor is also provided in conjunction with this control mechanism.

The whole indicating. dial mechanism is associated with this control mechanism so that the operator can by direct observation at any time select or determine what characteristics of operat ion his machine is performing. This mechanism is to include dial indicating means for showing the proper cutting speeds to utilize in connection with the particular work diameter being operated upon and these series. of data and information are directly interrelated with the movements of the control levers and mechanism associated therewith so that at all times the operator knows exactly what conditions are being obtained in his machine operation.

In conjunction with the electrically interlocking control mechanism and this dial indicating mechanism, apparatus is provided for automatically operating the main drive motor at a predetermined slow speed during gear changes and manipulations of the lathe transmission mechanism so that smooth. gear shifting is provided to permit ease of entrance of the various gear and clutch mechanisms and freedom from noise and damage to the lathe transmission.

Further features and advantages of the above general objects will be set forth in detail with reference to the following drawings in which:

Figure I is a front elevation, partly broken away to show the location of the electronic control apparatus of a typical tool room lathe incorporating the features of this novel transmission and control mechanism.

Figure II is an enlarged fragmentary front elevation showing the headstock end of the lathe in Figure I particularly illustrating the control dial mechanism for effecting the speed changes and control headstock transmission and the related feed box mechanism of the lathe.

Figure III is a left-hand end section of the headstock end of the lathe shown in Figures I and II on the line III-III of Figures I, II, and V.

Figure IV is a vertical transverse section through the headstock end of the lathe on the line IV-IV of Figures I and V, particularly showing the gear transmission in the headstock and feed box of the lathe, L

Figure V is a diagrammatic sectional view on the line VV of Figure IV showing the lathe transmission mechanism in the headstock and the feed train gearing of the feed box mounted on the headstock.

Figure VI is a fragmentary enlarged diagrammatic section on the line VI--VI of Figure III showing the gearing connecting the power from the feed box on the headstock to the various feed 4 and control rods going to the lathe apron mechanism.

Figure VII is an enlarged fragmentary sectional view on the line VII-VII of Figure 11 showing the detailed construction of the control knob and dial mechanism associated with the gear and speed changing apparatus.

Figure VIII is a fragmentary enlarged sectional view on the line VIIIVIII of Figure II showing the construction of the lubricating pump and con-. trol for connecting or disconnecting the leadscrew to the feed driving power of the lathe transmission.

Figure IX is an enlarged fragmentary sectional view on the line IX-IX of Figure II showing in detail the construction of the shifter mechanism for controlling the gears in the feed box of the lathe.

Figure X is an enlarged fragmentary sectional view on the line X-X of Figure IX.

Figure XI is an enlarged fragmentary sectional view on the line XI-Xf of Figure X.

Figure XII. is a fragmentary view on the line XII-X[I of Figure II showing the rear portion of the headstock showing the operating and interlocking control mechanism for the dial indicating and operating mechanism for the gear transmission and the electrical control mechanism of this transmission.

Figure IHII is an enlarged sectional view of one of the control discs indicated on the line XIII- XIII of Figure XII.

Figure XIV is an enlarged section on the line XIV-XIV of Figure XII showing the other mating control disc for the control dial mechanism.

Figure XV is an enlarged fragmentary diagrammatic showing of the transmission mechanism shown in Figure V indicating the relative position of the back gear, the high speed pulley drive clutch spool, and the feed drive gear transmission when the transmission is being operated for high work spindle speeds and fine feeds.

Figure XVI is a similar fragmentary view to that of Figure XV showing the transmission in 7 operative position when the lathe is being op rated 'in its normal range of back gear speeds and with standard feeds.

Figure XVII shows a similar diagrammatic view of Figure XV indicating the relative position of the headstock and feed gearing when the lathe headstock transmission is being operated in the lower portion of its back gear speeds, but with coarse threads being utilized for the tool feeding mechanism.

Figure XVIII is a diagrammatic showing of the periphery of the indicating data on the main control dial mechanism for the head stock transmission showing the relative position of the data when the lathe has its transmission operating as'in Figure XV for operating the lathe in the belt drive high speeds with fine feeds.

Figure XIX is a diagrammatic showing of the periphery of the part shown in Figure XII indicating the relative position of the control disc when the lathe transmission has been shifted to belt drive and fine feeds.

Figure XX is a section shown on the line QXX of Figure VII showing the position of -the main shifter control knob and operating disc when the lathe has its transmission positioned for operating in belt drive with fine feeds.

Figure XXI is a view similar to that of Figure XVIII but showing the position of the data when the operating and control dial apparatus is moved to the back gear position for operating the work spindle in its normal range of feeds when in the lower range of spindle speeds.

Figure XXII is a diagrammatic showing of the relative position of the control discs of Figures XII, XIII, and XIV shown diagrammatically when the transmission of the lathe headstock is operating in the back gear position with stand ard feeds.

Figure XXIII shows the relative position of the control disc knob when they control dial mechanism is operated to effect the back ear operation with standard feeds.

Figure XXIV is a similar diagrammatic view of the control dial data as shown in Figures XVIII and XXI but indicating the relative position when the lathe is being controlled for coarse threading with the work spindle operating only in the lower range of back gear speeds.

Figure XXV again shows diagrammatically the relative positions of the control discs and apparatus shown in Figures XII, XIII, and XIV and clearly indicates the restricting movement for the range of speeds which may be effected in the back gear position of the lathe while at the same time permitting coarse threads to be obtained at the tool feeding mechanism of the-lathe.v

Figure XXVI shows the control knob and associated discs when moved to its position permitting coarse threading to be obtained with the lathe transmission.

In Figure I is shown a typical. modern tool room lathe to which this invention has been applied, and which comprises a bed I which is mounted on a leg 2 at the headstock end and a leg 3 at the tailstock end of the bed l. On top of the bed is the headstock 4 and a tailstock 5 and the apron 6, cross slide 1 and tool post 8 in a conventional manner for such lathes. Power for rotating the work spindle 9 and work fixture IU of lathe headstock 4 in this particular illustrative example is derived from A. C. source of electrical power usually three phase sixty cycle 220 volt or 440 volt supply. This supply voltage is impressed on the transformers II and I2 mounted in the leg.3 of the lathe from which relatively high voltages may be obtained for the electronic control apparatus indicated generally at l3 which are contained on a panel l4 and comprise various electronic tubes l5 and [6, control unit [1, resistors l8, fuses I9, control relay 20, and other related starter switches 2| necessary to the complete control of all of the electrical apparatus in the lathe. The detail construction and circuit of this electronic control mechanism l3 forms no detail part of this invention itself but is related directly to the invention and interconnected with'it in the functions it is capable of carrying out in conjunction with the novel transmission mechanism for obtaining the desired operation of the lathe.

This electronic control mechanism l3 appropriately controls the main driv variable speed D. C. motor 22 mounted in the leg 2 of the lathe on a suitable motor bracket 23 in order to maintain the driving belts 24, Figure III, in proper tension at all times and to facilitate the easy.

raising of the motor by means of the eyebolt 25 to remove the belts when necessary. The belts 24 pass over the direct belt drive pulley 26 for effecting belt driving of the work spindle 3 and over the back gear pulley 21. Thus the two pulleys 26 and 21 are driven at all times by the main drive motor 22 which is capable of operating through a large range of accurately controlled variable speeds. Also the electronic control apparatus I3 is capable of rapidly stopping the main drive motor 22 for arresting spindle rotation and for causing reversal operation of motor 22 to reverse the work spindle when necessary.

The pulley 26 is journaled on a suitable bearing 28 on the work spindle 9 which work spindle in turn; is carr d on appropriate bearings 29 and 30 in the headstock housing 4. This pulley 26 isaadapted to be connected positively in driving relationship to the work spindle by means of a plunger clutch comprising the pin 3| carried in a bore 32 in the sleeve 33 fixed to the work spindle and carrying the bearing 29 which supports the rear end of the spindlev 9. This plunger 3| may be moved axially of the work spindle into the hole 34 in the disc 35 fixed to the pulley 26 by moving the operating spool 36 by appropriate means to be described. In this way the pulley 26 may be arranged for free rotation on the work spindle 9 when back gear driving is to be undertaken or may be locked positively in driving relationship on the work spindle 9 when the spindle is to be rotated in high speed direct belt drive.

The pulley 21 is fixed on the input shaft 31 by appropriate means 38 and which back gear shaft is mounted on suitable bearings 33 and 40 in-the headstock housing 4. This back gear shaft has fixed on it a pinion 4| which is adapted to be engaged by a gear 42 of the compound gear 43 shiftable axially on the spline portion ofthe back gear shaft 44 carried in suitable bearings 45 and 46 in the headstock housing 4. Now this compound gear 43 also has a pinion 4! which is adapted to engage the face gear 48 on the work spindle 9 when the gear 42 is engaged with the gear 4| so as to effect back gear driving from the pulley 27 to the shaft 31, gears 4l--42, and gears 4148 to the work spindle 9. Appropriate means for operating the compound gear 43 in predetermined sequential relationship with the clutch 36 will also be described later. Thus two speed ranges for the work spindle 9 is obtained from the motor 22, one the direct belt drive when the pulley 26 is connected by means of the clutch pin 3| to the work spindle 9 for high spindle speeds and a second range of back gear speeds when the back gear 43 is shifted to engage its gear 42 with the gear 4! and its gear 41 with the gear 48 at which time the pulley 26 is disengaged from driving relationship on the spindle 9.

Referring particularly to Figures V and XV, when the lathe is being operated at belt drive for high work spindle speeds, the back gear 43 is disengaged from the gear 4| and face gear 48 on 'the work spindle 9 as shown in Figure XV. Also, the clutch spool 36 has pushed the pin 3| into the hole 34 in disc 35, so that pulley 26 is in direct drivingengagement with the work spindle 9 and is being rotated by the -main drive motor 22 at the desired selected speed of the motor 22. Under these conditions feed power take off drive for operating the cutting tools at relatively fine feeds during these high spindle speeds, is derived from the small V belt pulley 43 fixed to the shaft 31 over which operates the feed'drive belt 50 which passes over a pulley 5|- 89 fixed upon the shaft 82 each side of the gear 58 serves to keep the gear 88 in proper axial position in engagement with the gear 88 and its proper relationship on the shaft 81.

On the shaft 51 is mounted a sliding compound gear 88 having a large gear 8| and a small gear 82. At the time of this driving of the work spindle at high belt speeds. the gear 8| is in mesh with the gear 83 of the double gear 84 journaled against axial movement on a stud 88 fixed in the headstock housing 4. Also, formed on the compound gear 88 is a clutch 88 which at this time engages a mating clutch 81 formed on the gear 58 so that driving power from the shaft 52 is transmitted through the gears 88-88 to the compound gear 88 and through the gears 8|-83 to the gear 84 journaled on the stud 88.

, Feeding power is then transmitted from the gear 84 through its gear teeth 83 to the idler gear 88 journaled onthe stud 89 fixed in the inward projecting portion of the feed box housing 18 fastened to the front portion of the headstock housing 4. The gear 88 drives the single toothed clutch gear 1| journaled on the shaft 12 fixed in the feed box housing 18 and which clutch gear 1| is adapted to engage by conventional single tooth clutching means 13 and 14 the corresponding clutch gears 15 and 18 likewise journaled on the shaft 12. The gear 18 drives directly the gear 11 fixed on the shaft 18 journaled in'suitable hearings in the feed box housing 18 while the gear 18 drives'the idler gear 19 journaled on the shaft 69 which in turn drives the gear 88 also fixed on the shaft 18 so that by selectively clutching the gear 1| with the gear 15 the shaft 18 may be driven in one direction and by clutching the gar 1|. with the gear 18 the shaft 18 may be rotated in the opposite direction through the idler 19. This provides the conventional feed reverse in head so that the feed may be reversed during thread chasing while maintaining the definite indexed relationship of the feed to spindle. rotation at all times.

Feeding power is then transmitted from the shaft 18 through gear 11 to gear 8| on the tumbler gear shaft 82 of the feed box 18 when cutting regular threads and leads and shaft 84 is driven from the gear 88, driving gear 83 when cutting metric threads and leads in a manner as set forth for a typical combined English and Metric feed box such as the exemplary showing of Figure V. Such a feed box is illustrated and described in Patent 2,239,443 of April 22, 1941. Since the details of the operating mechanism inthis combined English and Metric feed box forms no specific part in connection with this invention, it will, therefore, not be described in detail here except to point out that the drive as put into the feed box 18 from the shaft 18 as above pointed out is transmitted through the various gearing in the box and brought out from the shaft 84 through the change gear85, from where it is transmitted through an appropriate change gearing as best seen in Figures III and VI comprising a change gear 86 appropriately carried on a stud 81 on the quadrant 88 fixed on the lower box housing 89 by suitable bolts 98. The gear 88 in turn drives the gear 9| on the feed power input shaft 92 journaled in the lower box 89.

these results.

The feeding power from the shaft 82 is transmitted directly to the leadscrew through the clutch 98 connecting the gear 84 with the tubular member 98 fixed to the leadscrew 88 of the lathe. The ear 94. may also be shifted to the left, Figure VI, to engage its gear 91 with the gear 98 fixed on the feed rod 99 having an appropriate overload clutch |88 located between the gear 98 and the portion of the feed rod 801 18 to the lathe apron.

When it is desirable to operate the lathe in the back gear or lower range of speed and regular feed, the lathe transmission gearing is arranged as shown in Figures V and XVI. Under these conditions the compound gear 48 is moved to the right in Figure V so as to engage its gear 42 with the gear 4| and its ear 41 with face gear 48 on the work spindle 9. Also, the clutch spool 88 is moved to the right to withdraw the pin 8| from looking the pulley 28 to the work spindle 9 so that the pulley 28 will idle while being driven by the belts and main drive motor 22. Power is, therefore, being transmitted at relatively lower speed to the work spindle from the pulley 21 on shaft 91, through they compound gear 43 and the face gear 48 fixed on the work spindle 9 to thus provide a powerful slow speed drive in the work spindle in the lower ranges of cutting to be done.

At this time the clutch teeth 88 of the compound gear 80 are withdrawn from the clutch teeth 81 on the gear 58 while the gear 8| is brought into mesh with the gear |8| fixed on the work spindle 9 so that the gear 88 will be rotated directly from the work spindle in one to one ratio to provide a normal feed and thread range for the tool feed mechanism of the lathe as power is transmitted from the gear 8| to the gear 88 of the double gear 84 and through the transmission mechanismin the feed box already described. The main drive motor 22 at this time may be varied through its entire range of variable speeds by the electronic control apparatus I8 so as to provide a wide selection of spindle speeds in connection with this lower or back gear driving range in conjunction with the normal regular feeds and threads.

In some instances it is desirable to provide while the work spindle is rotating in the lower portion of the back gear range, coarse thread features in the feed mechanism by providing a relatively high rate of feeds and threads in comparison to spindle rotation. This is particularly desirable when coarse threads or screws are to be chased in the lathe. Under these conditions the headstock transmission gearing will assume the relative position of its parts as shown in Figures V and XVII in which the compound back gear 43 is moved an additional distance to the right but still maintaining its gear 42in engagement with the gear 4| and its gear 41 in engagement with the gear 48 on the work spindle 9, but also by this movement engaging its gear 42 with a gear I82 joumaled for free rotation on the work spindle 9. This gear I82 is also engaged by the gear 82 of'the compound gear 88 as this latter gear is moved to its extreme right position as shown in Figure XVII. At the same time by moving the gear 88 as described, its gear 8| will be again engaged with a gear 83a 'of the double gear 84 so that feeding power is then transmitted to the lathe feed mechanism from the gear 42 of the compound gear 43 through the gear |82 on the spindle 9 which drives the gear 82 of the compound gear 88 and through its gear 8| rotates the double gear 84 through its gear-88a which again transmits a feeding power to the feed box transmission 10 as described. In this way the spindle may be rotated at relatively low speed while a relatively higher rate of feed may be obtained for chasing coarse thread screws or the like.

In order to readily effect the high speed belt drive, the lower range back gear drive and the coarse threading position of operation for the work spindle of the lathe, a novel indicating and control dial device is provided at the front of the headstock as best seen in Figures II and IV. This device has three main control elements, namely the motor. speed control knob I03 which operates an appropriate control rheostat functioning in conjunction with the electronic control apparatus I3 for controlling the motor through its entire range of variable speeds. A push button control element I04 is provided which must be pushed in before any change in the ranges of gearing of the headstock transmission can be effected. Pushing in this knoboperates suitable electrical control mechanism associated withthe electronic control I3 whereby the motor, no matter at what speed at which it is rotating, is rapidly brought down to a predetermined slow speed and maintained at that slow speed of rotation during the changing of the mechanical mechanism in the headstock. transmission. A gear shifting control knob I is also provided which 4 the disc I06 to which the control knob I05 is attached and the three respective operating positipns I05a, I05b, and l05c-of the handle I05.

effects the operation of the various mechanical positions of the mechanism as shownin Figures XV, XVI,-and XVII when the push button I04 is held in to permit movement of the lever I05.

Referring particularly to Figures IV, VII, and XII the control knob I05 is fixed in a disc I06 which is rigidly attached to the rock shaft I01 by a suitable key I08 as best seen in Figure VII. This shaft I01 is journaled in a bearing I09 in the front end of the. headstock housing 4 and at its rear end in a suitable bearing I09a, Figure .XII. On this rock shaft I01 is formed intertermediate the length of the rock shaft I01 is fixedthe intermittent gear and Geneva motion arrangement II4 which in-turn operates in conjunction With an intermittent rack II 5 formed on the shifter yoke H6 slidably mounted on the rod II1 fixed in the headstock housing 4. The shifter yoke II2, referring to Figure V, reaches into the headstock transmission each side of the gear 42 of the compound back gear 43 so as to slide this gear 43 on the shaft 44. The shifter yoke H5 has-a portion IIIia which reaches into the headstock transmission and controls the sliding motion of the gear 60. On the front of the rock shaft I01 just inside the gearing I09 is formed the intermittent and Geneva motion gear I I8 which operates with an intermittent rack III! of the shifter yoke I20 which reaches and controls the sliding motion of the clutch spool 36 which connects or disconnects the belt driving pulley 26 to or from the work spindle 9.

In Figures XX, XXIII, and XXVI are shown When the handle I05 is in position I05a the gear transmission in the headstock is arranged for high speed belt driving with fine feeds. In position I 05b the gearing in the headstock is arranged for the lower range or back gear speeds with normal feed. And when in position I050 the normal range of spindle speeds usable in the lower portion thereof with coarse threads is available.

In Figure XV is shown the arrangement of the headstock gearing as above .described for high speed belt driving of the work'sp'indle with fine feeds and at which time the control knob I05 is in position I05a and the rock shaft I01 is so turned that the gear I I0 has its dwell portion I Illa in the dwell portion I Ila of the intermittent rack III of the shifter H2 so that the back gear 43 is shifted to the neutral position shown. The intermittent gear II4 will be positioned with its dwell portion II4a just entering the dwell portion I'I5a of the rack on the shifter H6, so that initial motion of the gear H4 in counterclockwise direction as the knob I05 is moved from position I05a to I05b will have no effect in moving the shifter H6 until the position I05b is almost reached, to in this way permit adequate travel of the back gear 43 into its driving position shown in Figure XVI, while moving the gear only through its relatively limited travel in the same period of time. Likewise the gear H8 on the rock shaft I01 has its tooth II8a just ready to enter into the tooth II9a of the intermittent rack H9 of the shifter I20 so that as the knob I05 is moved from position H151; to position I05b the pin 3| will be withdrawn to release the driving pulley 26 from the work spindle. Thus in moving the rock shaft I01 by the lever I05 from the position I05a to-position I05b the back gear 43, the clutch spool 36 and the gear 60 will be moved from thevposition shown in Figure XV to the position shown inFigure XVI. Likewise when the rock shaft I01 is moved by moving the lever I05 from position I051: to position I050 the rearrangement of the gearing in the transmission will be'that of the change from Figure XVI to Figure XVII. In this case the intermittent gear; H0 brings the gear teeth IIOb into operative relation with the rack teeth III of shifter yoke 2 so as to further move the back gear 43 to maintain its gear 42 into engagement with the gear M and its gear 41 in engagement with the face gear 48 while also bringing gear 42 into engagement with gear I02. During this time also it will be noted that the intermittent gear H8 has its dwell portion I I812 functioning so as to have no effect on moving the yoke I20 since the clutch spool .36 has been already moved to the point where the pulley 26 is disengaged from position I050 back through position I05b to position I05a.

In order to assist the operator in properly positioning the control knob I05 and disc I05 for the three main positions of belt drive, back gear drive, and coarse threads, an indicating pointer.

11 I2I is provided on the headstock housing 4 as indicated in Figures 111, IV, VII, XVIII, XXI,

and XXIV and on'the periphery of the disc I06 are provided the markings I22 for the belt drive,

I23 forthe back gear, and I24 for the coarse threadawhich respective marks may be brought into alignment with the indicating arrow I2I on the headstock 4 by moving the handle I05 to the three positions I05a, I051), and I050.

Referring particularly to Figures VII and X11, the knob I03 is rotated to control the electronic apparatus I3 through a control rheostat I25 carried at the rear of the headstock in a suitable cover plate I26 held in place by screws I21. The push rod I20 passing through the center of the rock shaft I01 is connected to the bushing I20 fixed to the knob I03 bythe pin I30 by means of the tongue I3I on the sleeve I23 which operates in a slot I32 in the push button I04. This push button is securely fixed to the end of the push rod I20 by threaded connections I33. On

the rear portion of the push rod I23 is fixed agear I34 by means of a suitable pin I35 which passes through the hub of the gear I34 and a sleeve I36 directly mounted upon the push rod I20. This gear I34 engages a gear I31 fixed on ,the shaft I 38 of the rheostat I25 so that when the push button I04 which moves the push rod I20 to the left in the Figures VII and XII to cause its outer end I 26a to engag the plunger I39 of the controlswitch I40 and to press in on this plunger I 33 to cause this switch to operate in conjunction with the electronic control mechanism I to eflect this slow predetermined speed of rotation for the motor 22.

The control knob I and its disc I06 cannot be moved unless the push button I04 is being held in, so that the motor 22 must always be operating at its slow predetermined speed before any changes of gearing can be made by manipulating the lever I05 and the disc I06. This apparatus is best shown in Figures XII, XIII, and XIV. On the rear end of the rock shaft I01 ls fixed a disc I 4| which is free to rotate with the shaft I01 as it is rocked to its three operative positions above described. Journaled to rotate on the sleeve I36 fixed to the push rod I26 is the disc I42 which is held against rotation relative to the headstock housing of the lathe by a set screw I43 threaded into the headstock housing 4 and projecting into an axially extending slot I 44 whereby the disc I 42 while it is prevented from rotating still permits the push rod I20 with its bushing I36 thereon to rotate freely inside its bore I42b. The axial extension of the slot I44 also permits the push rod and disc I42 to be moved axially with the axial movement of the push rod I20.

In the disc I42 is carried a, headed floating pin I45 which is normally confined with its head fully I in the disc I42 by the inner face I34a, as bestseen by reference to Figures XIX, XXII, and XXV, which show a diagrammatic peripheral decorresponding to the positions Illa, I001), and I060 for the lever I05. In order that the pin I46 may be entered into any of these three holes I46,

I41, and I40 it is necessary first to p h in on the push button I04 to operate the limit switch or control switch I40 to slow the motor 22 down to the predetermined slow speed so as to thereby it will be noted that when the push button I04 is pushed inwardly operating the switch I 40 the pin I45 will be withdrawn out of a hole in the disc I. Thus the rock shaft I01 may be rotated to any of its desired three positions and then the push button may be released and it will Jump back under the influence of the spring I40, Figure VII, to its normal operative position thus locking the shifting lever in any selected position. It will be noted by this arrangement that since the pin I45 normally engages the surface I34a of the gear I34 the push button can likewise not jump back into operative or normal motor speed operation unless the shifting mechanism is in one of the three operative positions.

It is to be noted in'this arrangement that the rheostat I25 isfor eflecting any of the variable speeds of rotation for the main drive motor 22 may be operated through its entire range by rotating the knob. I03 to the desired setting but this complete range of operation is limited only ,to the positions Mia and I05b for the control lever I05 of the headstock transmission. In other words, in this arrangement it is possible to utilize the complete speed range of the main drive motor 22 when the lathe is positioned in the high speed belt drive rang or the lower speed back gear drive range. However, it is to be distinctly noted that in this arrangement the spindle speeds obtainable when doing coarse threading are strictly limited to the lower range of the speed of rotation of the main drive motor 22, specifically in this embodiment to the lower thirty per cent of speed range of the motor when the headstock transmission is arranged for coarse threading operation. The understanding of this interlocking safety featur in connection with this control arrangement is best understood by reference to Figures XIX, XXII, and XIHV. In Figure XIX is shown the relative position of the parts of Figure 2m when the lathe is operating in the high speed belt drive position. Here it will be seen that the plunger I45 is entered into the bottomless hole I46 in the disc I so that the surface I344: of the gear I34 contacts th top of the head of the plunger I45 so that this gear I34 may be rotated freely through its entire distance of travel necessary to operate the rheostat I25 through its complete operative are for controlling the speed of the motor 22 through its entire range.

Referring to Figure m here we see the relative positions of the parts in Figure XII when the lathe is operating in the back gear or standard lower range of speed of operation with normal feed for the cutting tool. Here again the plunger I45 is entered into a bottomless hole I41 so that again the gear I34 may have fre rotation through its entire arc of travel for actuating the rheostat I25 for complete range of control of the motor 22.

'In Figure XXV is shown the relationship of the parts in Figure XII when the lathe is operating in the coarse threading position, at which time it would be dangerous and highly undesir- 

